Incorporation of sorbents, e.g., desiccants, into resin matrices has been revealed in several contexts. Formation of these resins into structural or functional shapes by various processes has been described in certain applications. Similarly, fillers have been added to structural molding resins. Low cost mineral or other fillers have been added to resin-containing compositions to extend the resin and reduce costs, while maintaining strength sufficient for the intended end-use application of the molded article. It is also a frequent practice to add reinforcing materials, such as glass fibers or beads to enhance mechanical properties of molding resins, e.g., hardness, tensile displacement, and so on. With reinforcing additives, just as with fillers, it has been found there are ranges within which the desired effects of extending the resin or reinforcing the molded article are accomplished while maintaining satisfactory injection molding and mechanical properties.
Nevertheless, molding compositions comprising reinforcing additives have not been entirely satisfactory for a number of end-use applications. For example, a molding composition having relatively high loading levels of reinforcing additives, such as glass fibers and glass beads have the affect of limiting the loading factor of sorbent additives which may be introduced into such molding compositions for optimal adsorption performance. However, with a corresponding reduction in the loading of reinforcing additives and an increase in the loading of sorbent additives, there was also a potential for a reduction in desirable mechanical properties, such as hardness, tensile strength, and other mechanical properties.
Thus, existing resin/sorbent matrices suffer from several drawbacks. The materials are often brittle and insufficient to survive standard drop testing. Additionally, particulate material may be released from the matrices thereby degrading part performance and/or device functionality. Due to the structure of these matrices, water may be adsorbed or absorbed at a faster rate, which in fact may be too fast for common manufacturing procedures. In other words, the ability for a part to adsorb water may be exhausted prior to its assembly in a device because environmental conditions are not controlled in the manufacturing area. Existing resin/sorbent matrices are often quite expensive to manufacture and use due to the use of exotic resin, additional processing steps and the use of multi-resin materials having phase boundaries. Additionally, existing resin/sorbent matrices may pose compatibility issues due to materials typically used as binders.
Accordingly, there is a need for improved resinous molding compositions, and more particularly, injection molding compositions and articles of manufacture made therefrom, wherein the compositions and manufactured articles retain high loading levels of sorbent additives without off-setting desirable mechanical properties of the resins.